What are the purposes for Frederick Douglass writing "What to the Slave Is the Fourth of July?" Part 1?

The purpose of Frederick Douglass writing "What to the slave is the fourth of July?" is that day reveal to him the gross injustice and cruelness which have been done to the slaves and of which he was also the victim. He attacks the celebration of the nation and reminds them of the dark day which they have witnessed. He felt that through his writing he will excoriate the country men which they deserved to be.